Pulp/Paper plant optimises wastewater treatment for environmental compliance

A turnkey monitoring solution from Hach^® has enabled a major paper/board producer to increase water reuse, save chemical costs & ensure discharge compliance. Grab samples were insufficient for process optimisation, so Hach delivered a 24/7 continuous monitoring system…

Wastewater from paper and cardboard production has a high organic load, but very low Phosphorus and Nitrogen values. The resulting C:N:P ratio is far from the conditions bacteria need for optimum digestion and good sludge sedimentation. Urea and phosphoric acid are therefore commonly used to address the nutrient imbalance.

Hach’s application experts proposed a drop-down 24/7 online process measurement and control solution that would manage the addition of nutrients continuously, reliably, and based on the actual incoming load. TOC (Total Organic Carbon), Ammonium and Phosphate analysers monitor the influent of the anaerobic stage, and Hach’s RTC-CNP control module manages the addition of urea and phosphoric acid. A second TOC value is measured at the effluent of the flash aeration.

It was necessary for the monitoring/control system to be located close to the treatment tank, so Hach’s inhouse engineering team designed a turnkey solution: A weather and corrosion resistant AnaShell^® analyser shelter; providing sufficient space for sample preconditioning systems, analysers, controller and the RTC-CNP real-time control module.

The stable, laboratory-like conditions in the insulated shelter with H-AC unit allow the analysers to achieve high accuracy and uptime. The equipment consists of a BioTector B7000i TOC analyser, EZ Series Ammonium and Phosphate analysers, an EZ9020 sample filtration panel, an SC1000 controller and the RTC-CNP. All instruments were pre-mounted, and the entire shelter underwent a factory acceptance test (FAT) prior to shipment for instant and sustainable operational reliability on site.

By choosing a Hach integrated system solution the customer was able to reduce their own project management workload, and at a time of high inflation and building material scarcity the project was realised quickly and on budget. The improved quality of the wastewater effluent will deliver a fast pay-back on the investment; the risk of fines has been mitigated, and environmental compliance is protected.

AnaShell analyser shelters are available in footprints ranging from 0.45 sqm to 12 sqm, housing up to ten analysers with their respective sample preconditioning systems. Applications cover all stages of industrial and municipal water cycles, from raw water, desalination, steam cycles, wastewater treatment to river monitoring.

Hach is the only true single-source supplier that develops, designs and manufactures the complete portfolio: from laboratory instruments and test kits, to process analysers, software solutions and turnkey integrated systems.